The present disclosure relates to a brake application device for a rail vehicle brake.
From European Patent Document EP 0 283 947 A2, a brake application device for rail vehicle brakes is known. The brake application device includes a brake actuator for the application and/or release of the brake and a force converter for converting the energy supplied by the brake actuator into a brake application movement. The force converter includes a shearing force measuring bolt arranged in the flow of force and equipped with at least one measuring sensor for the indirect and direct braking force measuring. The shearing force measuring bolt forms a hinge bolt of a hinge projecting through passage openings of at least two force transmission elements of the force converter which can be swivelled with respect to one another. Therefore, a sliding movement takes place at the shearing force measuring bolt under considerable braking forces. As a result, wear gradually occurs at the shearing force measuring bolt which carries the measuring sensor and therefore requires high expenditures for its manufacturing and mounting. This wear leads to an expensive exchange.
The present disclosure relates to an electromechanical brake application device in which the shearing force measuring bolt has a longer service life.
According to the present disclosure, the brake application device includes a brake actuator for application and release of the rail vehicle brake. Also included is a force converter for converting energy supplied by the brake actuator to a brake application movement. The force converter includes: (1) a shearing force measuring bolt arranged in a power transmission path; (2) at least one measuring sensor measuring breaking force either indirectly or directly; and (3) at least two mutually swivellable force transmission elements having passage openings. The shearing force measuring bolt forms a hinge bolt of a hinge, which hinge bolt penetrates the passage openings. A bushing, having radially interior edge recesses, is arranged radially between at least one of the passage openings and the shearing force measuring bolt.
The greatest shearing stress of the shearing force measuring bolt occurs in the area of the abutting planes of the force transmission elements. Axial edge areas of the bushings are subject to bending stress. Because of the radially interior edge recesses, the axial edge areas of the bushings are more flexible than the areas adjoining them, whereby high edge pressures are avoided between the bushings and the shearing force measuring bolt. The resulting evening-out of the tensions has a positive effect on the contact pattern of the sliding pairing which includes the bushing and the shearing force measuring bolt. Also, because of lower edge pressure, the stressing of the shearing force measuring bolt, whose manufacturing and mounting is relatively expensive, is reduced, and its service life is thereby increased.
According to an embodiment of the present disclosure, the bushing is non-rotatably held in the passage opening, in which case the bushing forms a sliding pairing with the shearing force measuring bolt. The bushing is constructed such that, with respect to wear conditions, such as hardness, surface roughness, material, etc., the bushing forms the sliding partner which tends to wear out earlier. The material of the bushing can be selected to be relatively soft for this purpose, and the shearing force measuring bolt can be selected to be correspondingly hard. As a result, gradually occurring wear takes place in the less expensive and easily exchangeable bushing instead of at the much more expensive shearing force measuring bolt.
According to the present disclosure, a carrying area of a radially exterior circumferential surface of the shearing force measuring bolt is formed by a cylindrically smooth surface without recesses or steps. Because of a lack of notches, this has a favorable effect on the endurance of the shearing force measuring bolt acting as a hinge bolt. As a result, the manufacturing of the shearing force measuring bolt is also easier and less expensive.
The shearing force measuring bolt may have an end-side bolt head with an enlarged diameter, in which bolt head an electronic sensor signal analyzing unit is accommodated. The shearing force measuring bolt therefore forms a complete measuring module which can supply signals to a braking force control. As a result, the shearing force measuring bolt can be integrated, as a separate measuring module into a control circuit of brake application devices. Such an arrangement may considerably simplify mounting, exchange or retrofitting. The shearing force measuring bolt may have only one standardized interface which can be connected to a braking force control device by persons not skilled in the field.
A measuring sensor, a connection wiring for the electronic sensor signal analyzing unit as well as the electronic sensor signal analyzing unit itself may each be provided redundantly. Thus, an increased reliability of the measuring arrangement may be achieved. In addition, a plausibility check can be carried out by comparing the measuring signals of two or more measuring circuits.
Other aspects of the present disclosure will become apparent from the following descriptions when considered in conjunction with the accompanying drawings.